At times, surrounding formation pressures can rise to a level to actually collapse well casing or tubulars. Other times, due to pressure differential between the formation and inside the casing or tubing, a collapse is also possible. Sometimes, on long horizontal runs, the formation surrounding the tubulars in the well can shift in such a manner as to kink or crimp the tubulars to a sufficient degree to impede production or the passage of tools downhole. Past techniques to resolve this issue have been less than satisfactory as some of them have a high chance of causing further damage, while other techniques were very time consuming, and therefore expensive for the well operator.
One way in the past to repair a collapsed tubular downhole was to run a series of swages to incrementally increase the opening size. These tools required a special jarring tool and took a long time to sufficiently open the bore in view of the small increments in size between one swage and the next. Each time a bigger swage was needed, a trip out of the hole was required. The nature of this equipment required that the initial swage be only a small increment of size above the collapsed hole diameter. The reason that small size increments were used was the limited available energy for driving the swage using the weight of the string in conjunction with known jarring tools. Tri-State Oil Tools, now a part of Baker Hughes Incorporated, sold casing swages of this type.
Also available from the same source were tapered mills having an exterior milling surface known as Superloy. These tapered mills were used to mill out collapsed casing, dents, and mashed in areas. Unfortunately, these tools were difficult to control with the result being an occasional unwanted penetration of the casing wall. In the same vein and having similar problems were dog leg reamers whose cutting structures not only removed the protruding segments but sometimes went further to penetrate the wall.
What is needed and is an object of the invention is a method and apparatus to allow repair of collapsed or bent casing or tubulars in a single trip using an expansion device capable of delivering the desired final internal dimension. The method features anchoring the device adjacent the target area, using a force multiplier to obtain the starting force for expansion, and stoking the swage as many times as necessary to complete the repair. These and other advantages of the present invention will become clearer to those skilled in the art from a review of the detailed description of the preferred embodiment and the claims below.